Slack message scheduler
Schedule channel messages to Slack
Draft once, pick your Slack channel next to any other network you post to, and set the time. Postauto holds the limit of 4,000 characters against your draft, departs every channel at that minute, and tells you what Slack did with it.
The rules
The Slack rules Postauto works to
Taken from Slack's own developer documentation, not from a marketing page.
Count your draft against this limit, and against every other network at the same time. No account needed.
| Content types | Channel messages |
|---|---|
| Character limit | 4,000 characters |
| Media rules | Files upload to the channel alongside the message |
| Account requirement | A Slack app you create at api.slack.com/apps for a workspace you administer |
| Availability | Live |
Network note
No review for your own workspace, and bot tokens do not expire, so a Slack channel is one of the few connections that never needs re-authorising.
Departure
What happens to a Slack post
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In the composer
The 4,000 limit is checked before you schedule
Write once, tick your Slack account alongside anything else you post to, and the counter runs against 4,000 characters while you type. Over the limit means you cannot schedule, not a failure tomorrow morning.
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On the board
Departures, not a spreadsheet of rows
Scheduled posts line up by time. You see what leaves next, what already departed, and what needs a look, without opening anything.
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After it leaves
A Slack result of its own
Every channel reports separately. A Slack rejection does not stop the other networks, and the network's own error text is shown on the board in plain language.
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At rest
Credentials encrypted with AES-256-GCM
Your Slack credentials are encrypted before they reach the database, are never logged in plaintext, and are decrypted only at the moment of publishing.
Per-channel results
You can see what each network did
One post, one row per channel. Departed channels carry a link to the live post; a failed channel carries the network's own error text, so you know whether to fix the wording, the media, or the connection.
Send the same draft to
Tick these next to Slack in the composer and they all leave at the same time.
Slack scheduling questions
What can I publish to Slack with Postauto?
Channel messages. Files upload to the channel alongside the message.
What is the Slack character limit?
4,000 characters. The Postauto composer checks this limit against every account you select before the post is scheduled, so nothing fails at departure time over length.
What do I need to connect Slack?
A Slack app you create at api.slack.com/apps for a workspace you administer.
Is Slack scheduling available on Postauto right now?
Yes. Slack publishing is live for every Postauto account today.
Anything specific to Slack I should know?
Slack documents 4,000 characters as the limit for best results and truncates well above it; Postauto enforces the documented figure. The bot has to be invited to a private channel before it can post there.
Can I post to Slack and other networks at the same time?
Yes. One composer publishes to any mix of your connected channels, and each network's limits are checked per selected channel. Every channel departs at the same scheduled time.
What happens if a Slack post fails?
Each channel reports its own result. If Slack rejects a post, your other selected networks still publish, the post is marked partial, and the board shows a readable error for the failed channel.
Is there a free plan?
Yes. The free plan includes 1 channel · 15 posts a month, no card required.
Next departure
Put Slack on the board
Connect the account, write the post, set the time. The free plan covers 1 channel · 15 posts a month.